The medical examiner conducted autopsies, and determined Catherine Murch's wound was self-inflicted. Toxicology results are pending, so the final report is not yet complete.

Fagan says 42-year-old Catherine Murch purchased a handgun from ontargetstl.com on July 28, and that gun was used in the killings. He also said the gun was obtained legally and that all bullets recovered in the home came from that weapon.

There is no evidence to indicate anyone other than Catherine shot the weapon.

Eight-year-old Mary Claire Murch was shot once in an upstairs room. Mitchell Murch III, 10, was shot multiple times in a room on the lower level of the home.

Fagan says though the exact chain of events is difficult to determine, the situation happened very quickly.

Catherine's husband, Mitchell Murch II, was also on the lower level of the home when the crimes happened. Fagan says the incidents happened so quickly there was not much opportunity for him to respond.

Catherine did not leave a suicide note.

Fagan says Mitchell Murch II made two 911 calls. One call went to Glendale, and the other went to Kirkwood. He says the calls were made from a cell phone and one call was dropped.

The investigation revealed Catherine had a mental health history, but Fagan declined to comment further. He says over the last few weeks she was having a hard time, and that the family was under some financial strain.

Fagan says there were many internet searches made by Catherine in the days leading up to the incident regarding suicide.

Every aspect of this case was investigated thoroughly, and every possibility was considered. Fagan says it appears Catherine loved her children very much, and that she had struggled for several years.

NewsChannel 5's Leisa Zigman spoke with a clinical psychologist Friday about mothers who murder their children.

Dr. Helen Friedman says we tend to think of murder as an act of hate. But, as hard as it is to process, she said some people can see it as an act of love.

"Often the thought of separation from ones children is just so painful that she doesn't want her kids to miss her, or doesn't want to be separated from them, or the thought of them going on without her just feels incomprehensible," said Dr. Friedman.

Friedman also added, in some cases, a mother does this to spare her children from what she sees as a threat, either real or imagined.

There is video of Catherine at a gun shop, but that video has not been released.